Added more printing of errors to myisamchk.

mysys/mf_iocache.c:
  Write error message if failed seek.
sql/table.cc:
  Fixed buffer overflow bug:
  - It's not enough to check for mysql_version to to detect partion indicator as the version may have been updated by mysql_upgrade.
storage/myisam/ha_myisam.cc:
  Don't log same error twice.
  Don't reset log_all_errors if it's set
storage/myisam/mi_check.c:
  Fixed bug that caused repair() to not report error if called twice (as when doing retry)
  More printing of errors.
storage/myisam/sort.c:
  Set my_errno in case of out of memory errors.